Glass is used in a variety of products ranging from buildings to automotive products. Depending on the end use of the glass, the glass will be required to have certain color and other performance properties like infrared radiation absorption, ultraviolet radiation absorption, visible light absorption, total solar energy absorption, etc.
In order to produce glass having a specific color and other performance properties, various additives are added to a base glass composition. A typical base glass composition comprises Na2O, CaO, MgO, Al2O3, SiO2 and K2O. Typical additives to a base glass composition include compounds containing iron, cobalt, nickel, selenium, chromium, titanium, etc.
For certain commercial applications, blue colored glass having certain solar performance is required. A multitude of compositions for forming blue glass are well known to those of skill in the art. For example, U.S. Pat. No. 6,313,053 discloses a composition that yields a blue colored glass. To form the blue glass, additives such as ferric oxide (Fe2O3) and a reducing agent such as coal are added to a base glass composition. The reducing agent is used to control the amount of ferrous oxide (FeO) in the composition.
Glass compositions having a lower redox ratio are generally preferred over those having a higher redox ratio because glass compositions having a lower redox ratio are easier to melt, refine, and cool, therefore generally less costly to process.
The present invention provides a novel glass composition for forming blue colored glass comprising iron oxides, neodymium oxide and/or copper oxide. The glass composition of the present invention can have an iron redox ratio of 0.15 to 0.65, for example, from 0.25 to 0.50, and solar energy blocking properties.